3 files changed, 37 insertions, 9 deletions
diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index 52ea87a48..32f3e2947 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -100,7 +100,7 @@ func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
 	if cfg.GCEImage == "" {
 		cfg.GCEImage = env.Name
 		gcsImage := filepath.Join(cfg.GCSPath, env.Name+"-image.tar.gz")
-		log.Logf(0, "uploading image to %v...", gcsImage)
+		log.Logf(0, "uploading image %v to %v...", env.Image, gcsImage)
 		if err := uploadImageToGCS(env.Image, gcsImage); err != nil {
 			return nil, err
 		}
@@ -436,15 +436,10 @@ func uploadImageToGCS(localImage, gcsImage string) error {
 		Mode:     0640,
 		Size:     localStat.Size(),
 		ModTime:  time.Now(),
-		// This is hacky but we actually need these large uids.
-		// GCE understands only the old GNU tar format and
-		// there is no direct way to force tar package to use GNU format.
-		// But these large numbers force tar to switch to GNU format.
-		Uid:   100000000,
-		Gid:   100000000,
-		Uname: "syzkaller",
-		Gname: "syzkaller",
+		Uname:    "syzkaller",
+		Gname:    "syzkaller",
 	}
+	setGNUFormat(tarHeader)
 	if err := tarWriter.WriteHeader(tarHeader); err != nil {
 		return fmt.Errorf("failed to write image tar header: %v", err)
 	}
diff --git a/vm/gce/tar_go1.10.go b/vm/gce/tar_go1.10.go
new file mode 100644
index 000000000..88a5d1fda
--- /dev/null
+++ b/vm/gce/tar_go1.10.go
@@ -0,0 +1,14 @@
+// Copyright 2018 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+// +build go1.10
+
+package gce
+
+import (
+	"archive/tar"
+)
+
+func setGNUFormat(hdr *tar.Header) {
+	hdr.Format = tar.FormatGNU
+}
diff --git a/vm/gce/tar_go1.9.go b/vm/gce/tar_go1.9.go
new file mode 100644
index 000000000..a26ecbdd5
--- /dev/null
+++ b/vm/gce/tar_go1.9.go
@@ -0,0 +1,19 @@
+// Copyright 2018 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+// +build !go1.10
+
+package gce
+
+import (
+	"archive/tar"
+)
+
+func setGNUFormat(hdr *tar.Header) {
+	// This is hacky but we actually need these large uids.
+	// GCE understands only the old GNU tar format and prior to Go 1.10
+	// there is no direct way to force tar package to use GNU format.
+	// But these large numbers force tar to switch to GNU format.
+	hdr.Uid = 100000000
+	hdr.Gid = 100000000
+}